1. Field of the Invention
This invention relates to musical tone control apparatuses using piezoelectric sensors and sensing devices having pressure sensibility used for electronic musical instruments.
This application is based on Patent Application No. Hei 10-184437 and Patent Application No. Hei 10-217146 both filed in Japan, the contents of which are incorporated herein by reference.
2. Description of the Related Art
Conventionally, there are provided a variety of technologies for musical tone controls using pressure sensitivity. For example, the paper of U.S. Pat. No. 4,043,241 (which corresponds to Japanese Patent Publication No. Sho 54-19338) discloses a musical shoe, i.e., a shoe-type musical instrument that generates musical tones in response to motion of a foot or leg of a human operator (or performer). Herein, electronic circuits and a speaker are stored inside of a case body having a ship-like shape. In addition, multiple switches are arranged on a lower side surface of the case in connection with names of musical tones respectively. The performer puts the case body on his or her foot. So, the performer is capable of playing melody sounds by turning on the switches with his or her foot steps.
The aforementioned shoe-type musical instrument is conventionally designed to have a capability of merely changing over the names of the musical tones to be produced. There is provided another conventional technology which performs musical tone controls in response to foot motions, which is designed for the system of electronic musical instruments which are generally capable of performing the musical tone controls with respect to multiple music elements such as tone volumes and tone colors. For example, the paper of U.S. Pat. No. 5,714,706 (which corresponds to Japanese Patent Application, Publication No. Hei 9-68973) discloses a musical tone control apparatus using a foot sensor of a shoe insole type, which is equipped with piezoelectric sensors. Herein, the musical tone control apparatus controls musical tones by detecting pressures that a performer applies to the piezoelectric sensors with a toe and a heel respectively.
In addition, some musical tone control apparatuses are designed like percussion instruments by employing pad units that are beaten by sticks or else. Herein, the pad unit is constructed using a sensing unit which is coupled to a pad skin to be beaten and which has a sensitivity in sensing beats applied to the pad skin. So, the musical tone control apparatus generates musical tone control signals in response to outputs of the sensing unit. For example, the paper of Japanese Patent Application, Publication No. Hei 9-297576 discloses an electronic drum device which is an example of the aforementioned musical tone control apparatus. In addition, the paper of Japanese Patent Application, Publication No. Hei 6-175651 discloses an electronic drum, wherein a piezoelectric sensor is securely attached to a pad plate that is fit into a pad rubber (i.e., pad skin). Herein, the pad plate is connected together with a base plate at the periphery thereof by means of cushion members. Thus, the piezoelectric sensor detects vibrations of the pad plate which vibrates when the pad rubber is beaten.
By the way, the conventional musical tone control apparatus of the shoe type employs a sensor unit which is shown in FIG. 11A and FIG. 11B. Such a sensor unit suffers from a problem as follows:
A piezoelectric sensor xe2x80x9caxe2x80x9d is securely attached to a displacement disc face plate xe2x80x9cbxe2x80x9d, which is arranged to face with a reference disc face plate xe2x80x9ccxe2x80x9d via a spacer xe2x80x9cdxe2x80x9d. Herein, the reference disc face plate c is brought into contact with a contact surface of a shoe that a sole of a foot of a person comes in contact with. The spacer d is formed with regard to a part of an area by which the displacement disc face plate b faces with the reference disc face plate c. That is, the sensor unit has a structure in which the displacement disc face plate b is subjected to cantilever support. For this reason, the sensor unit has specificity in a direction that external force is applied. In a situation where force is selectively applied to the spacer d, a dead zone (or insensitive area) occurs around the spacer d. Therefore, an output level of the sensor unit differs in response to a direction and a position to step a foot, regardless of an amount of force to step a foot. Namely, the conventional musical tone control apparatus of the shoe type has somewhat a peculiarity in sensing the pressure that the performer""s foot applies to the sensor unit.
In addition, the conventional musical tone control apparatus employs an insole-type foot sensor, so it suffers from a problem as follows:
Suppose a situation that the performer steps his or her foot constantly to operate the foot sensor at a portion where the performer intends to touch with a sole of the foot. In such a situation, however, a position of a toe and a position of a heel are slightly shifted from intended positions on the piezoelectric sensor in response to an angle and a direction to step the foot. For this reason, the conventional apparatus must perform xe2x80x9cunintendedxe2x80x9d musical tone control. In other words, the conventional apparatus lacks fidelity as an input device (or input interface) of the foot motion.
It is an object of the invention to provide a sensing device for an electronic musical instrument that is capable of constantly producing a same output in response to an amount of force applied thereto, regardless of a direction to apply the force from the external.
It is another object of the invention to provide a musical tone control apparatus of a shoe type, which has a high fidelity as an input interface for inputting foot pressure.
It is a further object of the invention to provide a musical tone control apparatus of a percussion instrument type which is capable of producing a same sensor output in response to same beat force applied to a pad skin surface, regardless of directions of applying the beat force.
It is a still further object of the invention to provide a musical tone control apparatus of a percussion instrument type which is capable of providing visual information in response to a manner to beat a pad skin surface.
According to a first aspect of the invention, there is provided a sensing device for an electronic musical instrument, which is constructed by a sensor case containing a piezoelectric sensor, a sensor fixing member, a disc plate pressure member and an annular elastic member.
The sensor case made of ABS resin is attached to a bottom surface of a footwear, e.g., a sole of a shoe. The sensor fixing member is securely mounted on the disc plate pressure member in such a way that a center part of the sensor fixing member securely engages with a center part of the disc plate pressure member. Herein, both of the sensor fixing member and disc plate pressure member are formed in thin-disc-like shapes made of stainless steel having springiness. The piezoelectric sensor is securely mounted on the sensor fixing member so as to have a sensitivity responsive to pressure, which is applied to a bottom surface of the disc plate pressure member from the external and which is transmitted thereto via the disc plate pressure member and the sensor fixing member. The annular elastic member elastically supports the sensor fixing member within the sensor case.
The sensor fixing member has elastic deformability so that the sensor fixing member is located to face with the disc plate pressure member with an air gap in which the sensor fixing member is capable of deforming within a limit of elasticity thereof. Thus, the electronic musical instrument performs musical tone control in response to an output of the piezoelectric sensor which responds to a foot motion applied to the footwear.
Incidentally, a cover made of stainless steel and a damp cover made of rubber are attached to a bottom surface of the sensor case.
According to a second aspect of the invention, there is provided a shoe-type musical tone control apparatus which is put on a footwear such as a shoe.
The shoe-type musical tone control apparatus is constructed using at least one sensing unit, which is designed like the aforementioned sensing device. Herein, the sensing unit containing a piezoelectric sensor is put into an opening hole of a surface layer member, which is attached to a toe portion or heel portion of the sole of the shoe. Thus, it is possible to perform musical tone control in response to foot motion (such as step motion) which is applied to the shoe and is detected by the sensing unit. Incidentally, it is possible to further provide a pendulum-type sensor which is attached to an instep portion of the shoe to detect vibrations applied thereto in response to the foot motion of the shoe.
According to a third aspect of the invention, there is provided a musical tone control apparatus of a percussion instrument, which is basically constructed using a pad unit stored in a pad storage portion of an upper case made of ABS resin. Herein, the pad unit is constructed by a pad skin unit made of rubber material and a sensing unit, which are assembled together. The pad skin unit has a beat surface to be beaten, while the sensing unit contains a piezoelectric sensor, which is attached to an assembly of a sensor fixing member and a radial pressure member both of which are formed in circular-disc-like shapes made of stainless steel, for example. A center part of the sensor fixing member having elasticity in deformation is securely fixed to a center part of the radial pressure member, while the piezoelectric sensor is attached approximately to a center of a back of the sensor fixing member. Thus, when a beat is applied to the beat surface of the pad skin unit so that corresponding pressure is transmitted to the piezoelectric sensor via the radial pressure member and sensor fixing member, the sensing unit produces a signal in response to beat force, by which a musical tone control is performed with respect to tone volume, for example.
In addition, switches are arranged in connection with an outer periphery of the pad storage portion corresponding to a hollow formed at a prescribed position of the upper case. By detecting on/off states of the switches, a musical tone control is performed with respect to tone color, for example.
Further, light emitters are arranged on a periphery of the beat surface of the pad skin unit. Herein, each of the light emitters is constructed using a LED, luminance of which is controlled in response to switches which are located in connection with the outer periphery of the pad storage portion. Thus, it is possible to provide visual information using the light emitters, each of which is lighted when a beat is applied to its surrounding area.